Noncorrosive antifreeze liquid



Patented Apr. 23, 1940 UNITED STATES PATENT OFFICE Kenmore, N. Y.,

assignors to Carbide and Carbon Chemicals Corporation, a corporation of New York No Drawing.

Application February 9, 1938,

Serial No. 189,590

13 Claims.

The invention relates to antifreeze liquids of the type employing an alcohol as a freezing point depressant, and is particularly concerned with corrosion prevention in such liquids by means of 5 improved corrosion inhibiting materials.

The use of alcohols as freezing point depressants in cooling fluids is well known, and many difierent monohydric and polyhydric compounds have been proposed for this purpose. :The most common of these include such as methanol, ethanol, propanol, ethylene glycol, other glycols and polyglycols, and glycerol. In the present invention any of these alcohols may be used as freezing point depressants, and inhibitor materials are proposed for maintaining protection of metal in contact with cooling fluids containing any of the monohydric or polyhydric alcohols.

It is generally accepted that alcohols are not inherently corrosive toward metals, but in cooling fluids where they are normally diluted in various degrees with Water, they are subjected to conditions which often give rise to, or induce in the fluids, a corrosive action toward metals. In the usual automobile cooling system, aeration of the cooling fluid during circulation is diflicult to avoid. Adventitious addition of exhaust gasses and other impurities into the cooling liquid is ol'ten encountered, and localized overheating of the fluid is not at all uncommon. Through one or more of these factors corrosive conditions may be induced in the cooling fluid, and become sever enough to cause metal attack unless steps are taken to avoid or repress such action. It has, therefore, become customary to employ corrosion inhibiting materials with alcohol antifreeze solutions, and a large number of chemical compounds, in the nature of addition agents to the alcohol, have been proposed for this purpose. Prior inhibitors have not, however, been entirely 40 satisfactory, since they often fail in eiflcient protection for all metals of the cooling system, are short lived in the protection afiorded, or are deficient in other respects.

It is an object of our invention to provide improved alcohol cooling fluids in which induced corrosive action is repressed or prevented. It is a further object to provide inhibitor materials adapted to protect all metals of a cooling system during normal usage and life of an alcohol cooling fluid.

We have found a group of compounds which are capable, when added individually to an alcohol cooling fluid, of providing excellent corrosion protection. These substances may be broadly classed as aromatic nitro-hydroxy compounds, including materials of a structure in which both the nitro and hydroxy groups are directly attached to the aromatic nucleus, or the hydroxy group is positioned only in a side chain.

60 Particularly suitable inhibitors are the so-called side chain are not so readily available, but as represented by the satisfactory action of the compound m-nitrobenzyl alcohol, it appears that a corrosion inhibiting function is characteristic to all of the aromatic nitro-hydroxy compounds. When present in the cooling fluid in amounts from about 0.05% to 1.0% by weight of the alcohol, any of these compounds will satisfactorily protect iron, brass, copper, solder and aluminum, and their corrosion protective action is operative in both alkaline and slightly'acid solutions.

Some of these materials may impart a color to the cooling fluid. This is not detrimental to the corrosion inhibiting function of the materials, but where undesirable for other reasons, color formation can be avoided by addition of a specific decolorizing agent. lFOI this purpose a material such as ammonium molybdate has been lound suitable, and can be used in conjunction wlth the nitro-hydroxy compound. While these new inhibitors are individually capable of providing satisfactory metal protection, there can be used in cooperation therewith other inhibitor materials, including, for example, compounds like sodium nitrate for further specific protection of aluminum or other metals, an oil or a compound adapted essentially to retard leakage, and an alkaline material such as sodium carbonate for imparting to the solution a reserve alkalinity. Formulae including these other components, which have proven to be especially eifective when incorporated in an ethylene glycol cooling solution, are represented by the following, in which the amounts of specific ingredients are expressed in percent by weight of the glycol:

, Formula I Formula II Picric acid 0 5 0.4 Ammonium molybdate d 3 0.3 Sodium carbonate O 5 0. 4 Sodium nitrate 0 3 0. 3 Oil (90 parts mineral oil, parts su1- fonatud neuts-foot oil) 2.0

reference herein to nitro-hydroxy compounds. Many other modifications in a complete inhibitor mixture will be evident to those skilled in the art, and are included within the scope of the invention, where the aromatic nitro-hydroxy compound serves as the necessary and essential corrosion preventive component. The invention should not be limited other than as defined by the appended claims.

We claim:

1. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive an aromatic nitro-hydroxy compound, in which a nitro group is directly attached to the aromatic nucleus.

2. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive an aromatic nitro-hydroxy compound in an amount about 0.05% to 1.0% by weight of the alcohol, said compound having a nitro group directly attached to the aromatic nucleus.

3. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing as the essential corrosion preventive a nitro-derivative of the group consisting of phenol, resorcinol, cresol, thymol and benzyl alcohol, said inhibitor being present in an amount of about 0.05% to 1.0% by weight of the alcohol.

4. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing about 0.05% to 1.0% by weight of the alcohol of picric acid as the essential corrosion preventive.

5. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing about 0.05% to 1.0% by weight of the alcohol of dinitrophenol as the essential corrosion preventive.

6. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor containing about 0.05% to 1.0% by Weight of the alcohol of trinitroresorcinol as the essential corrosion preventive.

7.. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor mixture consisting or picric acid,. ammonium molybdate, sodium carbonate, and sodium nitrate.

8. A noncorrosive antifreeze liquid comprising an alcohol and an inhibitor mixture consisting of picric acid, ammonium molybdate, sodium carbonate, sodium nitrate, and an oil.

9. A noncorrosive antifreeze liquid comprising ethylene glycol and an inhibitor mixture consisting in percentage by weight of the glycol of about 0.5% picric acid, about 0.3% ammonium molybdate, about 0.5% sodium carbonate, and about 0.3% sodium nitrate.

10. A noncorrosive antifreeze liquid comprising ethylene glycol and an inhibitor mixture consisting in percentage by weight of the glycol of about 0.4% picric acid, about 0.3% ammonium molybdate, about 0.4% sodium carbonate, about 0.3% sodium nitrate, and about 2.0% oil.

11. Method of inhibiting corrosion of metals by an ethylene glycol cooling fluid in contact therewith which comprises contacting said fluid with the metal in the presence of an inhibitor mixture consisting of picric acid, ammonium molybdate, sodium carbonate, and sodium nitrate.

12. Method of inhibiting corrosion of metals by an ethylene glycol cooling fluid in contact therewith which comprises contacting said fluid with the metal in the presence of an inhibitor mixture consisting of picric acid, ammonium molybdate, sodium carbonate, sodium nitrate, and an oil.

13. Method of inhibiting corrosion of metals by an alcohol cooling fluid in contact therewith which comprises contacting said fluid with the metal in the presence of an inhibitor containing as the essential corrosion preventive 3. nitroderivative of the group consisting of phenol, resorcinol, cresol, thymol and benzyl alcohol, said inhibitor being present in an amount of 40 about 0.05% to 1.0% by weight of the alcohol.

FRED R. WHALEY. I-IEADLEE LAMIREY. 

